1. Field of the Invention
The present invention relates to an exposing device and an imaging magnification adjusting method, and in particular, relates to an exposing device and an imaging magnification adjusting method used for an image recording device or the like.
2. Description of the Related Art
Conventionally, an image recording device for recording an image by scanning on a photosensitive drum rotating in a predetermined direction (main scanning direction) with a light beam modulated according to the image in a direction substantially orthogonal to the predetermined direction (sub scanning direction), is known.
According to the image recording device, an exposing device comprising a multi beam light source for emitting light beams from a plurality of light emitting points disposed with a predetermined interval in the sub scanning direction, and a lens group for collecting the light beams on the photosensitive drum can be used for recording the image at a high speed or the like.
Moreover, recently, in the exposing device using the multi beam light source, changeover of the imaging magnification of the light beam according to a plurality of resolutions, such as 2,400 dpi (dot per inch), 2,438 dpi, 2,540 dpi, or the like, is desired.
Conventionally, the imaging magnification has been changed over by increasing the number of lenses in the exposing device and moving the lenses according to the resolution.
However, according to the conventional technique, since the number of lenses should be increased, the device is bulky and expensive.
In order to solve the problem, as shown in FIGS. 8A to 8C, a technique for changing the imaging magnification in an exposing device comprising an optical fiber array 14 as the multi beam light source, a first lens 16 and a second lens 18, with the first lens 16 and the second lens 18 fixed and only the optical fiber array 14 provided movably, has been provided.
However, in the case the imaging magnification is changed by moving only the optical fiber array 14, as shown in FIGS. 8A to 8C, the image forming position of the light beam 11 is displaced. Moreover, since the light beam 11 transmitted the first lens 16 can be a diverging light, a parallel light or a converging light, the lens design is difficult.